Certifying Magnets - A process

I propose that a regular, repeatable method to test and validate a magnet's integrity be set up.

A standard, of sorts, to simply help us identify good from bad. I know this idea has popped up and been kicked around a lot, But we have yet to actually develop any regular system to validate magnets, unless I have missed something. Easily possible. There are snatches here and there of x or y process to test, but can we bring it all together and make it concise? ^^'

Of course, things such as saline solution exposure and visible inspection should be in this category, but what other tests should be executed? Destructive and non-destructive?

Comments

I know everyone brings up salt water soaks all the time, but there has to be a better thing to try soaking in... vinegar? milk? I don't know. The body is way more corrosive than salt water, so it seems we should test magnetic coatings with something more corrosive, too.

Agreed. The solution, or at least the most commonly used one, should be compatible with coatings, and Incompatible with the coated material. Heating salt water may create more reactivity as well, correct? What about agitation?

What kind of salt water is going to be the most aggressive? Research needs to be done... :3

I'm just wondering what annihilating the coating would be useful for? You can't implant that magnet now, and it seems like a waste of $60 from a consumer standpoint. Mild salt water is used because consumers just want a readily accessible test with results that are easy to read to see if any part of the magnet is exposed. For all I know, the body doesn't even break down TiN (but please correct me if I'm wrong).

Basically, I just want to know why a more aggressive test is needed :)

The point wasn't to annihilate the coating, but to use a harsher test that better simulates what's going on in the body. If a coating is stable for, like, weeks in say, vinegar, then maybe it would be stable indefinitely in the body.

Well, so there are two separate things worth testing- coating integrity (if it is doomed to fail because the magnet is exposed already), and coating stability/durability (whether an initially good coating will eventually be broken down by the body). The body puts a lot of stress on coatings, which is why this is such a hard problem. Also, there is still a lot of debate over which coatings are bioproof enough without adding too much thickness. See: every topic where people mention parylene. ;)

So we are very quickly exiting my knowledge level on this subject but I believe the heated salt speeds up the reaction (I remember reading that some where). I can't remember from bio but was the body acidic or a base? Perhaps a solution that is acidic or base, based on that answer?

Alternately, we could just shove them in all sorts of random environments to see what would happen. Salt water, fish tank, dead fish, etc. Maybe the compost bucket isn't quite a good mimic of the human body, but surely all of it put together would be a decent analogue.

I say this mostly tongue in cheek as I'm still a bit woozy from Friday's surgery.

It's not just how the coating responds to the acidity (blood is a bit alkaline around pH 7.4 from memory) but also how the coating would respond to the body's response (inflammation, attempts in phagocytosis, all that gist). This is a dynamic process which cannot be simulated statically by a chemical (it will be like trying to find a material that can withstand going from 10,000 degrees to 0 degrees cycles by putting them in 5,000 degree heat). From memory cell cultures are used for in vitro biocompatibility testing (pre-clinical trials), but animal trials (phase I clinical trials) is always the next step before going into a human body.